a. Field of the Invention
This invention relates to novel fused .gamma.-pyrone- and .gamma.-pyridone-2-carboxylic acid derivatives, to processes for their preparation, to methods for using said derivatives, and to pharmaceutically acceptable compositions of said derivatives.
More specifically, the present invention relates to novel fused .gamma.-pyrone- and .gamma.-pyridone-2-carboxylic acid derivatives possessing valuable pharmacologic properties. For example, these derivatives are useful for treating allergic conditions at dosages which do not elicit undesirable side effects. Furthermore, the present derivatives exhibit useful antimicrobial properties. The combination of these pharmacologic properties together with a low order of toxicity render the fused .gamma.-pyrone- and .gamma.-pyridone-2-carboxylic acids of the invention therapeutically useful.
B. Description of the Prior Art
Only a rather limited number of reports dealing with fused .gamma.-pyrone- and .gamma.-pyridone-2-carboxylic acids are available. One report concerns fused .gamma.-pyrone-2-carboxylic acid derivatives of benzofuran, as described by J. B. Wright, U.S. Pat. No. 3,816,467, issued June 11, 1974. However, in this reference, the .gamma.-pyrone-2-carboxylic acid is fused to a benzofuran whereas the .gamma.-pyrone-2-carboxylic acids of this invention are fused to a benzopyran. Only recently fused .gamma.-pyrone-2-methyl derivatives of benzopyran have been prepared by F. M. Dean, et al., J. Chem. Soc., Chem. Comm., 440(1974), in order to prepare the pyranopyrone nucleus of the fungal metabolite citromycetin. In addition, more recently, fused .gamma.-pyrone-3-carboxaldehyde derivatives of dihydronaphthol have been prepared by D. Kaminsky, U.S. Pat. No. 3,862,144, issued Jan. 21, 1975. The compounds of the present invention are distinguished from the prior art compounds by having substituents at a variety of positions on the nucleus, most notably a carboxylic acid function at position 2 as well as having hetero atoms in positions 1 and 6 of the nucleus.